Types of muscle and muscle fibre

All skeletal muscles are voluntary muscles, they are under our conscious control (e.g. biceps). Involuntary muscles work without our conscious control and include the walls of our digestive system and blood vessels. Cardiac muscle is a specialist type of involuntary muscle that makes up the thickest layer of the heart. Fast twitch muscle fibres with a high speed and force of contraction are used for short, intense exercises. Slow twitch muscle fibres that are resistant to fatigue are used for long distance events.